Tropical Fish Forums

[CREXK2]

Hi I'm unfamiliar with killifish and I was just wondering if a few people could answer a couple questions of mine:
what region of the tank do killifish usually hang out
are theyu aggressive
can they be kept in groups
and what do they usually eat
thanks..

[UncleWillie]

Hello and welcome, CREXK2!
There are so many killifish from various regions of the world, that there will be a decent amount of variation in biology depending on genus or species. But there are some broad generalities made regarding your questions..

What region of the tank?
Generally, most killifish are oriented around the surface. Obvious traits such as superior (upturned) mouths show that most feed off the surface of the water. This mouth also gives them the ability to breath in the fine layer of water nearest the surface where dissolved oxygen is highest. However, some killifish will stick towards the middle of a tank. But you must remember that most killies are found in very shallow water where vegetation is dense. Many killifish are found in waters less than 1 foot in depth. Some larvae cannot orient themselves for swim-up unless they are in less than 6". But that is getting off topic..

Are they aggressive? Can they be kept in groups?
Depends. I know of some killies that are fairly peaceful for some time. However, my experience shows this to be the exception rather than the rule. Many males, once they reach sexual maturity will get quite aggressive towards other males. They will protect a particular territory and fend off any others.
Some killifish groups consist of a single male and harem of females. If this is the case, if there are any small males in the group, they may be killed. However, some killifish seem to be peaceful towards individuals of the same and different species.

What do they usually eat?
in the wild, many are insectivorous, feeding on insects that have fallen onto the water's surface. They prefer meaty foods like aquatic insects and worms - some even specialize on snails. Although, some species incorporate a decent amount of vegetative matter in their diets as well. So, the are generally omnivores.

[CREXK2]

Thanks. Do you think I could put one in my tank? Its a planted 29 gallon with a shoal of red eyed tertas.

[UncleWillie]

I don't see why not. Just gotta pick a species and go from there.